Sagger pin



United States Patent 2,90 9 J sAGoER- N Edward Schramm, .assig nor to.Onondaga Pottery Company, Syracuse, N.Y., a corporation of New York HApplication February 1 9 57, Serial 641,525 3 Claims. (c1. 2s 115s).

are fired at an elevated temperature to produce vi-trous ware.

After the articles have been fired, they are dipped into a glazesolution and are placed in boxes formed of refractory material and knownas saggers. In order to support articles of flatware which have been socoated with the glaze material, the articles are supported on the endsof pins mounted in the inner surface of the sagger wall. These saggerpins are conventionally triangular in cross section and are positionedso that one apex of the triangular formation engages the under side ofthe dish or plate, the pins serving to effectively support the articleswhile they are fired the second time to fuse the glaze material over thesurface of the ware.

It is an object of this invention to provide a new and improved saggerpin which will prevent the problem of chipping in connection with thefiring of articles of glazed ware.

Prior to this time, when flatware, or dishes, or the like, was preparedto be fired, the ware was dipped into the glaze and then placed in'asagger wherein each piece of the ware was supported at three points uponsagger pins.

'The sagger was then closed and put into the kiln to fire the glazedware. During this firing process, the ends of the sagger pins fused tothe bottom of the ware. After the firing was finished, and while thesagger was cooling, tensile stresses developed at the point of contactbetween the sagger pin and the ware. (This is due to the fact that thesagger, the ware, and the sagger pins, each have a differentexpansivity.) These strmses combine to cause the fused sagger pin tochip the ware. That is, a small piece of the fired ware would adhere tothe sagger pin at the point of contact during the cooling of the firedsagger, thus leaving a depress-ion in the ware. This depression givesthe ware an undesirable appearance and can not be corrected in the pieceof fired'ware and therefore, it is considered very undesirable in theprocess of firing glazed ware.

Up to this time, several elforts have been made to solve this problem ofchipping. One of these efforts proceeded along structural lines. Thismethod was to make the pin body weaker so that it would be possible toreach a condition where the pin, rather than the ware, would fail duringthe cooling, thus causing a portion of the pin to break oif, rather thanchipping the ware. This solution proved to be impractical for the reasonthat such pins would not support the ware unless they were increased insize to a considerable extent and this was impossible since an increasein the size of the pin body wouldl mean a decrease in the amount of warethat could be carried and fired in a sagger.

Another method of attempting to solve the problem ofpin chipping was tocontrol and set up a balance between the expansivity rate of each of thesagger, sagger pin, and ware, in order to eliminate the tensile stresseswhich caused the chipping. Although this solution at first.seemedpractical, it later proved to be impractical for the reason thatit became impossible to maintain this balance over any substantialperiod of time for the saggers themselves, when used' continuously,would show a decrease in the rate of expansivity, thus upsetting thebalance.

With my new and improved sagger pin, the drawbacks of previous attemptshave been obviated and it is now possible to practically eliminate theproblem of pin chipping.

It is therefore an object of my invention to provide a sagger pin whichwill not chip the ware when the pin separates from the ware afterfiring.

The invention consists in the novel features and in the combinations andconstructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanyingdrawings in which like characters designate corresponding parts in allthe views.

In the drawings- Figure 1 is a cross section of a portion of a saggerwith a plurality of plates mounted therein.

Figure 2 is a plan view of an individual sagger pin.

Figure 3 is a cross sectional view taken on the line 33 of Figure 4.

Figure 4 is a cross sectional view taken on the line 4*4 of Figure 3.

Figure 5 is a cross section of the ware and sagger pin immediately afterseparation.

1 indicates a sagger in which a plurality of glazed plates 2 are mountedfor firing. These glazed plates are supported on a plurality of saggerpins 3, shown in Figure 2. Each of the sagger pins is coated, at the endthereof which is to support the glazed plates, with a coating material 5which entirely surrounds the end of the pin (see Figures 3 and 4). Thesagger pins 3 are formed of a suitable ceramic material, and the pinsare fired before they are placed in the sagger box to provide sufiicientstrength and rigidity to support the plates 2 and prevent them fromsagging while they are being fired.

This coating material is of a type which will fracture more easily thanthe glazed Ware, after the glazed ware has been fired. That is to say,when the sagger pins are separated from the plates 2 after firing andupon cooling, the coating 5 will fracture more easily' than the glazedplate 2 so that, upon cooling, contraction of the pins and the plate,tensile stresses between the pin and the plate 'will cause a potrion ofthe coating 5 to fracture and adhere to the plate, forming aprotuberance, or nipple 6, see Figure 5, on the plate. Thisprotuberance, or nipple, is then conveniently removed by griding itflush with the under side of the piece of ware.

The coating 5 is of refractory material which is relatively porous andwhich is more frangible than the piece of ware whereby, upon cooling ofthe loaded sagger after fiiring, any stresses developed between the pinand the piece of ware will result in that portion of the coatingcontacting the ware severing from the pin. Such coating material mayconsist of kaolin or zirconium silicate. The coating may be applied bydipping the end portion of an unfired pin body into a heavy slurry ofthe refractory material and then firing the pin in the usual way toproduce a strong pin body having a relatively low absorption with themore porous coating at the end having a higher absorption. Also,previously fired pins may be dipped into the slurry of refractorymaterial and refired at hiscuit temperatures. In both instances, therefractory material becomes bonded to the end of the pin.

' r V 2,908,960 I, I

Due to the fact that the coating is more frangible '7 than the glaze, orthe body of the piece of ware, the coating will fracture when stressesare developed between the pin and the piece" of Ware, with the resultthat afragment of the coating will remain adhered to the under side ofthe dish,'as distinguished from the conventional situation Where afragment or chip is pulled out of the piece of ware, due to the factthat the fused end of the pin body is less frangible than the piece ofware.

The coating 5 permitsthe pin body to be made as dense as desired forstrength and need not be increased in cross sectional area. Likewise,the control of expansivity of the pins and saggers becomes of little orno importance. Further, the use of such a coating will minimize the sizeof the protuberance, or nipple, adhered to 15 ware during the firing ofthe ware, said pin comprising an elongated body formed at the endsupporting the ware with a coating of refractory'mater-ial bonded to thebody of the pin, said refractory material being more frangible than theWare and the pin body whereby, upon cooling of the ware, that portion ofthe coating contacting the Ware Will sever from the pin.

'2. A sagger pin as set forth'in claim 1, wherein said coating is formedof kaolin.

3..A sagger pin as set forth in claim 1, wherein said coating isformedof zirconium silicate.

References Cited in the file of this patent UNITED STATES PATENTS

